Cardiac assist systems are used to aid patients with chronically and unacceptably low cardiac output who cannot have their cardiac output raised to acceptable levels by traditional treatments, such as drug therapy. One particular type of cardiac assist system currently used is a cardiomyoplasty.
Essentially a cardiomyoplasty provides a muscle-powered cardiac assist system. As seen in U.S. Pat. No. 4,813,952 of Khalafalla, incorporated herein by reference, the cardiomyoplasty is a cardiac assist system powered by a surgically-modified muscle tissue, such as the latissimus dorsi. In particular, the latissimus dorsi is wrapped around the heart. An implantable pulse generator is provided. Implantable pulse generator senses contractions of the heart via one or more sensing leads and stimulates the appropriate nerves of the muscle tissue with burst signals to cause the muscle tissue to contract in synchrony with the heart. As a result, the heart is assisted in its contractions, thereby raising the stroke volume and thus cardiac output. Besides delivering therapeutic electrical pulses to the muscle, the pulse generator is quite often also coupled so as to also provide therapeutic electrical pulses to the heart. See, for example, U.S. Pat. No. 4,735,205 of Chachques et al., incorporated herein by reference.
Central to a system such as that disclosed in the Chachques patent is that the skeletal muscle graft be transformed from a slow twitch to a fast twitch muscle. Typically this has been undertaken only through careful monitoring of the skeletal muscle graft by medical personnel. In particular, this meant the patient had to repeatedly return to the physician's office to have the pulse generator, and thus the electrical conditioning regime, adjusted as the muscle was transformed. Thus there exists a great need to permit the automation of the conditioning regime to avoid the patient from having to undertake repeated trips to the physician's office. Patients as well as physicians would thus be well-served by a device which automated the electrical conditioning regime.